1821231 - webrtc/RTCPeerConnection-getStats.https.html fails intermittently because the first packet transmitted is RTX

Status: RESOLVED FIXED

(Core :: WebRTC: Audio/Video, defect)

Description

[Byron Campen [:bwc]]

It seems that sometimes the first RTP packet out of the sender is using the RTX ssrc. This causes an unmute event, but we don't get any outbound-rtp stats for it, because the stats query code is not looking at stats for RTX.

I need to read up on how the stats api is supposed to treat rtx independent of the stream being retransmitted.

Comment 1

[Byron Campen [:bwc]]

Heads-up on this; do you know off the top of your head how this ought to be functioning?

Comment 2

[Nico Grunbaum [:ng, @chew:mozilla.org]]

Thanks for the heads up. The RTX being treated separately makes sense, though it is new to me.

Comment 3

[Byron Campen [:bwc]]

I looked, and webrtc-stats says:

"RTX streams do not show up as separate RTCOutboundRtpStreamStats objects but affect the packetsSent, bytesSent, retransmittedPacketsSent and retransmittedBytesSent counters of the relevant RTCOutboundRtpStreamStats objects."

It looks like libwebrtc either does not do any of this summing-up work for us, or maybe this summing-up does not work properly when only RTX has been sent. I'll need to investigate further.

Comment 4

[Byron Campen [:bwc]]

It looks like libwebrtc is doing at least some of this totaling-up:

https://searchfox.org/mozilla-central/rev/cd2121e7d83af1b421c95e8c923db70e692dab5f/third_party/libwebrtc/audio/channel_send.cc#803,805-806,812

But I'm guessing it is not setting this when it sends rtx:

https://searchfox.org/mozilla-central/rev/cd2121e7d83af1b421c95e8c923db70e692dab5f/dom/media/webrtc/jsapi/RTCRtpSender.cpp#351

I'm thinking we may want to check this instead of that timestamp:

https://searchfox.org/mozilla-central/rev/cd2121e7d83af1b421c95e8c923db70e692dab5f/dom/media/webrtc/jsapi/RTCRtpSender.cpp#394

Comment 5

[Byron Campen [:bwc]]

Hmm. It looks like the totaling-up is only being done for audio, which is pretty weird. So we'll need to total this stuff up ourselves.

Comment 6

[Byron Campen [:bwc]]

Attachment: Bug 1821231: Take RTX stats into account for outbound-rtp stats. r?ng

Comment 7

[Byron Campen [:bwc]]

https://treeherder.mozilla.org/jobs?repo=try&revision=2799ef378bddeecd224849702278f1a69e478154
https://treeherder.mozilla.org/jobs?repo=try&revision=3ceb7f9c0034a9210aad2bf7cee1cfbbe429f026

Comment 8

[Byron Campen [:bwc]]

Try looks fine.

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/cda424bfe16c
Take RTX stats into account for outbound-rtp stats. r=ng

Comment 10

[Marian-Vasile Laza]

https://hg.mozilla.org/mozilla-central/rev/cda424bfe16c